IN DEVELOPMENT Moving Y motor to the back outside

Staff Member

So I played a bit and unfortunately the loop belt we have is too short even if we move the motor axis to the same height as the Y drive axis.
So if we wanna do this we need a longer belt.

Given that I thought lets just mirror the current part to mount it from the outside and lets see how long the belt must be, maybe it is a length we can source...
Here is the result:
If I didn't do a major miscalculation then the belt should be around 180mm which is one of the lenghts I can easily order on Amazon...

Also we could just move the plane the motor is mounted to to the same plane as the upper screw case is, then we can move the motor a little upwards too if the belt is not long enough...

Staff Member

Hmm on ebay I can get additional lengths though 186 might be too long and moving the motor further down is not possible with this design, maybe more to the back but I think I am going for 180 and then adjust the mount to fir that size...

Ah! Allow me to suggest that you add a mounting plate on the inside of the case so the Perspex is clamped (between the plate and the bracket) over a wide area. People will see that bracket as a hard point, even if they know better, and will be tempted to apply significant force to it when moving the BigBox. It won't stop all breakage of the Perspex but it could help.

I have been playing with thoughts like these of my own. I'm also playing with the idea to add a bigger plate on the back with rubber mounts spaced wide to stop to much play. This way we can also reduce the vibrations along the back plate. The adaptor plate should be as heavy as practically possible to lower any resonance frequency as it is not as annoying.

Please notice I say "practically possible" as a heavy plate would not be so practical

Have you ordered those? If so put me down for 2 (always keeps spares), if not I will order those.

To avoid "cutting" the hole at the back bigger, what about indirectly driving the y axis via another pulley? So motor on the back, with a GT2 16 pulley that connects to a tiny rod mounted inside the big box below the Y axis rod with 2xGT2 pulleys which in turn drives the large Y axis pulley?

The idea being that you use the existing hole that is there for the motor cable currently. Would need a totally different mount for the motor (or mount it over the hole) and a mount inside for the new rod/pulleys but would not require any more cutting, just drilling.

Otherwise Ill get the Dremel out, mine is the plywood so simple enough to modify.

Staff Member

Received two 180mm closed loop belts today, going to print the mirrored mount and see how the dimensions will work before I cut the back plane...

Off topic: think I am going to print them on my fresh switched to 1.75mmm filament UM2 because I think I wanna go for the 1.8° steppers for X on my IDEX setup before I am trying the next print on the BB...

Thinking about this, How much more room on Y will moving the motor outside give us? From what I can tell the max gain will be 6mm. I could be wrong. This of course is perfect as with the IDEX heads we lose about 4mm from the total 200mm available on the bed.

So if a thinner Y Motor mount could be made then that "should" give the same amount of improvement on Y as externalising the motor. I am measuring to the Pulley on the Y rod that the motor drives for my max space calculations.

It was a heavy night last night so please do check that the above makes any sense.

Oh and the only other thing which puts the price up a bit would be a Nema14 Astrosyn or equivelent Damper if there is such a beast.

OR... Is it possible to shave 4 - 6 mm of the existing motor mount? Looking at my motor there is quite a bit of gap between the motor and rear frame. Obviously would not want it touching but if it was possible to get the gap down to 1 - 2mm then that should give the full 200mm build surface on Y.

And/Or... on the right extruder for IDEX, move the endstop screw underneath instead of the rear and that would give another 4 - 5 mm. Obviously the end stop switch on the right would need to moved from rear to underside also.

I just ordered a bunch of 6mm GT2 closed belts and got 10 of each for $36 Let me know if you or anyone else wants a set as I'm not sure when I will be able to start on this. But at least now I got what I need.

I also measured roughly >180mm and might mount it on a larger bracket with some spacers if too long.

180mm length, 90 teeth

186mm length, 93 teeth

188mm length, 94 teeth

190mm length, 95 teeth

192mm length, 96 teeth

194mm length, 97 teeth

Anyone wants a set? Giving away 8 sets as long as I actually recieved enough.